The present invention relates to a non-aerosol dispenser, especially a hand-held non-aerosol spray can which emits a liquid spray upon manual actuation of a valve.
The present invention constitutes an alternative to aerosol spray dispensers which use pressurized gas as a propelling force. Gases currently in use contain hydrocarbons which have increasingly come under attack as a serious contributor to air pollution. For example, hydrocarbons released in the atmosphere can react with nitrogen oxide and sunlight to form smog.
There have heretofore been proposed gasless spray dispensers which propel the product by mechanically generated propelling forces. For example, pump type dispensers have been proposed which require a mechanical displacement of a pump stem each time that a user dispenses a spray. Such dispensers are incapable of storing energy and thus eject the contents in the form of intermittent spray bursts rather than a prolonged spray.
Other dispensers have been proposed which rely upon mechanical actuation, as exemplified by U.S. Pat. Nos. 3,815,787; 3,195,168; 2,728,097; and 2,738,905.
In U.S. Pat. No. 3,815,787, a dispenser is disclosed wherein a piston is mounted within a helical groove formed on an inside surface of a cylindrical container. By rotating the container relative to a top discharge portion of the dispenser, the piston is caused to ascend within the container to discharge product located thereabove. However, since the helical groove faces the contents chamber, it is necessary to confine the liquid within a bag, or else the liquid would escape along the helical groove. The need for bags may increase the manufacturing costs and presents the risk that the bag can become ruptured as the result of being pinched between the piston and either the helical groove or vertical guide slots which receive radial tabs of the piston.
In U.S. Pat. No. 3,195,168, an axially threaded rod is provided which extends axially within the container and carries a threaded follower. Disposed above the follower is a piston which seals against the inside surface of the contents chamber. The rod is rotated by means of a knob mounted at the bottom of the container. A spring between the follower and piston transmits motion from the follower to the piston to store energy. By rotating the rod, the follower and piston are raised to dispense the contents. To prevent the follower from rotating, the follower and the wall of the contents chamber are formed with complementary non-circular cross-sections. Such a non-circular cross-section reduces the inner volume of the container and thus reduces the amount of liquid product which can be held. Also, the need for a separate actuator rod and turning knob may increase the cost and complicate the assembly of the apparatus. While the spring effectively stores energy, it does not transmit the energy to the piston as uniformly across the area of the piston as would be desired, thereby resulting in a less-than-optimum spray pattern.
In U.S. Pat. Nos. 2,728,097 and 2,738,905 dispensers are disclosed which involve the need for a threaded rod and which present the problem of leakage of product past a dispensing piston.
It would be desirable to provide a relatively lowcost, easily assembled, non-aerosol dispenser which does not require that the product be stored in a bag and which, if a bag is used, minimizes the risk of the bag being ruptured.
It would also be desirable to provide such a dispenser which makes it possible to store propulsion energy so that a continuous discharge can be effected with a highly uniform spray pattern.